We’ve been tinkering with the DNA of other species for thousands of years. We just didn’t know what we were doing.

Starting about ten thousand years ago, humans began to steer the evolution of animals and plants. Our ancestors collected certain seeds instead of others, started to plant them in gardens, and gradually produced domesticated crops. They didn’t know which genetic variants they were choosing, or how those genes helped build new kinds of plants. All they knew was that some plants were better than others. Over thousands of years, for example, an innocuous bush called teosinte turned into tall stalks with gargantuan seeds–otherwise known as corn.

Continue reading “The Evolution of Cavities” →

In 1837, Charles Darwin scribbled a simple tree in a notebook and scrawled above it, “I think.”

That little doodle represented a big idea: that species were descended from common ancestors. They looked different from each other today thanks to the differences that evolved after their lineages split.

Continue reading “Redrawing the Tree of Life” →

About 1800 years ago, a volcano in northern Nicaragua exploded. The crater formed by the eruption slowly filled like a rain barrel. Eventually the water rose high enough to warrant the title of lake. Today it is called Lake Apoyeque. Although Lake Apoyeque is over 300 feet deep, the rains have a long way to before they reach its brim. Lake Apoyeque remains ringed by volcanic cliffs towering as high as 1200 feet. And yet, despite its young age and its remote location, it is filled with fish.

For thirty years, Axel Meyer, an evolutionary biologist now at the University of Konstanz in Germany, has journeyed to Lake Apoyeque and other lakes of Nicaragua to study the evolution of their fish. He and his colleagues have caught cichlids and sequenced their DNA. By comparing their genes, the scientists can work out how the fish spread across the country. At Lake Apoyeque, for example, they found that the cichlids shared a number of mutations with the cichlids of Lake Managua nearby. The fish of Lake Apoyeque have accumulated relatively few mutations of their own. Meyer and his colleagues studied those mutations to estimate how long it took for their genetic diversity to evolve. They concluded that the cichlids came from Lake Managua to Lake Apoyeque only about a century ago.

Continue reading “The Angelina Jolie Project” →

In 1941, a rose killed a policeman.

Albert Alexander, a 43-year-old policeman in Oxford, England, was pruning his roses one fall day when a thorn scratched him at the corner of his mouth. The slight crevice it opened allowed harmless skin bacteria to slip into his body. At first, the scratch grew pink and tender. Over the course of several weeks, it slowly swelled. The bacteria turned from harmless to vicious, proliferating through his flesh. Alexander eventually had to be admitted to Radcliffe Hospital, the bacteria spreading across his face and into his lungs.

Continue reading “When You Swallow A Grenade” →

Welcome to the Loom. I’d like to use my first post here to introduce myself and my blog, as I set up camp at National Geographic.

My relationship with National Geographic goes way back–back to a prehistoric era when I didn’t even know what blogs were. My first story for the magazine appeared in 2001. It was an exploration of the ways scientists figure out how old things are–the universe, the Earth, the animal kingdom, our own species. It was the first article I wrote as a freelance writer, having just left Discover, where I had been on staff for ten years. I’m forever grateful to National Geographic for welcoming me into the uncertain world of freelance journalism with journeys to mountaintop observatories and to the oldest patches of Earth still exposed on the planet’s surface.

Continue reading “Moving Day” →